![Page 1: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/1.jpg)
From Dark to Light Hydrogen and the First Stars
Tabitha Voytek, Carnegie Mellon University
1
SCI-HI Project Collaborators: Jeff Peterson (CMU), Aravind Natarajan (CMU/Pitt) *Omar Lopez-Cruz (INAOE), Jose-Miguel Jauegui-Garcia (INAOE), Edgar Castillo (INAOE) *Other future collaborators in Mexico
![Page 2: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/2.jpg)
2
Background
Instrument
Deployment
Analysis
Results
Improvements
![Page 3: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/3.jpg)
Observations with the SCI-HI experiment focus on first star formation during the Cosmic Dawn.
Image: http://www.nasa.gov/mission_pages/planck/multimedia/pia16876b.html
SCI-HI Observations
3 Background Deployments Results
Instrument Analysis Improvements
![Page 4: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/4.jpg)
4
Background
![Page 5: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/5.jpg)
All 21-cm observations are made using Hyperfine splitting of the ground state of hydrogen.
1s 1S1/2
ΞE β 1420 MHz β 21-cm
5 Background Deployments Results
Instrument Analysis Improvements
![Page 6: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/6.jpg)
Hyperfine splitting is energy differentiation caused by the spin alignment of the proton and electron.
Image from: http://aliceingalaxyland.blogspot.com/2009/04/mini-spinni-antics-of-atoms-in-space.html
6 Background Deployments Results
Instrument Analysis Improvements
![Page 7: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/7.jpg)
Neutral hydrogen (HI) gas can be found in the Interstellar and Intergalactic Medium (IGM).
7
Hydrogen 21-cm Emission Contours for M51
Image from: http://www.haydenplanetarium.org
Background Deployments Results
Instrument Analysis Improvements
![Page 8: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/8.jpg)
All-sky 21-cm spectrum experiments measure the average redshift evolution of HI gas in the IGM.
Image: Pritchard and Loeb, Nature, 2010
8
2/1)1)(1( zTs
initial
T
T
spaceb
Background Deployments Results
Instrument Analysis Improvements
obs
obsemitz
![Page 9: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/9.jpg)
In particular, the SCI-HI experiment focuses on the all-sky averaged signal during the Cosmic Dawn (z~20).
Image: Pritchard and Loeb, Nature, 2010
9 Background Deployments Results
Instrument Analysis Improvements
SCI-HI Measures Here
![Page 10: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/10.jpg)
10
Instrument
![Page 11: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/11.jpg)
Three primary components were considered in designing the SCI-HI instrument.
Antenna Working Frequencies: 40-130 MHz
RF Electronics Switch, amplifiers, filters and cables
Computer Analog to Digital Conversion and Fourier Transform
11 Background Deployments Results
Instrument Analysis Improvements
![Page 12: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/12.jpg)
The SCI-HI antenna went through several different iterations before settling on the HIbiscus design.
Trombone Antenna HIbiscus Antenna v1 HIbiscus Antenna v2
12 Background Deployments Results
Instrument Analysis Improvements
![Page 13: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/13.jpg)
Data was collected with the preliminary SCI-HI instrument in June 2013 on Isla Guadalupe.
13 Background Deployments Results
Instrument Analysis Improvements
![Page 14: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/14.jpg)
At the time, the instrument had a single antenna and relied on 12V car batteries for DC power.
14 Background Deployments Results
Instrument Analysis Improvements
![Page 15: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/15.jpg)
15
Deployment
![Page 16: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/16.jpg)
Terrestrial radio frequency interference (RFI) is a significant problem in radio astronomy.
16 Background Deployments Results
Instrument Analysis Improvements
![Page 17: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/17.jpg)
We evaluated current and potential experiment sites for their RFI environmental quality.
17 Background Deployments Results
Instrument Analysis Improvements
![Page 18: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/18.jpg)
At each site, quality was investigated using a portable antenna and spectrum analyzer.
18
Algonquin Guadalupe
Background Deployments Results
Instrument Analysis Improvements
![Page 19: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/19.jpg)
We chose to deploy SCI-HI at Isla Guadalupe based upon the excellent RFI environment.
19
FM band as measured with the SCI-HI instrument
Background Deployments Results
Instrument Analysis Improvements
![Page 20: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/20.jpg)
20
Analysis
![Page 21: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/21.jpg)
Data collection includes both the sky signal and calibration source signals.
21 Background Deployments Results
Instrument Analysis Improvements
![Page 22: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/22.jpg)
Sky signals collected with the HIbiscus antenna are dominated by the Milky Way Galaxy.
22 Background Deployments Results
Instrument Analysis Improvements
![Page 23: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/23.jpg)
This Milky Way Galaxy signal varies over each day due to the antenna beam sky coverage.
Daily Signal Variation at 70 MHz
23 Background Deployments Results
Instrument Analysis Improvements
![Page 24: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/24.jpg)
Calibration utilizes the Milky Way Galaxy foreground model and daily mean/variance.
Beam Averaged Sky Temperature:
ππΊππ π‘, π = πΞ© πΊππ π, π, π π΅(π β π0 π‘ , π β π0 π‘ , π)
πΞ© π΅(π β π0 π‘ , π β π0 π‘ , π)
GSM Model comes from de Oliveira-Costa et al. (2008)
ΟΒ² Fitting:
π2 π = Ξπππππ π‘, π β ΞππΊππ π‘, π2
π‘
Daily Mean Subtraction:
Ξπππππ π‘, π = πππππ π‘, π β πππππ π·π΄π(π)
ΞππΊππ π‘, π = ππΊππ π‘, π β ππΊππ π·π΄π(π)
24 Background Deployments Results
Instrument Analysis Improvements
![Page 25: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/25.jpg)
KΞGSM calibration is most successful when a full day of data is collected.
25 Background Deployments Results
Instrument Analysis Improvements
![Page 26: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/26.jpg)
Example KΞGSM Mean and Fit
After calibration, foreground removal was done using a simple polynomial fitting and subtraction.
26
πππ10 ππΊπ(π) = ππ πππ10(π
70 ππ»π§)π
π
π=0
ππππ π = πππππ π·π΄π π β ππΊπ(π)
Daily Fit:
Daily Residuals:
Background Deployments Results
Instrument Analysis Improvements
![Page 27: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/27.jpg)
27
Results
![Page 28: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/28.jpg)
Preliminary data collection in June 2013 gave good results, but further improvements are necessary.
KJNC Calibrated
KΞGSM Calibrated
Predicted 21-cm Signal Models
28 Background Deployments Results
Instrument Analysis Improvements
![Page 29: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/29.jpg)
29
Improvements
![Page 30: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/30.jpg)
Problem: DC battery is unreliable. Solution: Replace battery with an AC gas generator.
30 Background Deployments Results
Instrument Analysis Improvements
![Page 31: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/31.jpg)
Problem: DC battery is unreliable. Solution: Replace battery with an AC gas generator.
31 Background Deployments Results
Instrument Analysis Improvements
![Page 32: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/32.jpg)
Problem: Antenna frequency range is too small. Solution: Build multiple scaled antennae.
32
70 MHz Scale
100 MHz Scale
Background Deployments Results
Instrument Analysis Improvements
![Page 33: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/33.jpg)
Problem: Self-generated RFI seen in data. Solution: Double Faraday cage for computer.
33
Double Faraday Cage
Computer inside inner Faraday Cage
Background Deployments Results
Instrument Analysis Improvements
![Page 34: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/34.jpg)
Problem: Isla Guadalupe still not remote enough. Solution: Find more remote sites.
34
Time Series of the FM band for June 1st, 2013 data
Time Average of the FM band for June 1st, 2013
Background Deployments Results
Instrument Analysis Improvements
![Page 35: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/35.jpg)
Problem: Isla Guadalupe still not remote enough. Solution: Isla Socorro/Clarion and/or Marion Island.
35
Guadalupe
Socorro Clarion
Marion Island
Background Deployments Results
Instrument Analysis Improvements
![Page 36: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/36.jpg)
With these changes, the SCI-HI experiment will help us better understand the first stars.
Foregrounds
Current Best Results (KΞGSM)
Predicted 21-cm Models
36 Background Deployments Results
Instrument Analysis Improvements
![Page 37: From Dark to Light: Hydrogen and the First Stars](https://reader033.vdocuments.site/reader033/viewer/2022052323/5590756e1a28abe7118b4687/html5/thumbnails/37.jpg)
S C I β H I Sonda CosmolΓ³gica de las Islas para la DetecciΓ³n de HidrΓ³geno Neutro
37